Rotor for waste comminuting device



April 29, 1958 E. J. HAMMES 2,832,548

ROTOR FOR WASTE COMMINUTINQ DEVICE Filed Oct. '7, 1954 ATTO/P/VIFYS V United States Patent 2,832,548 ROTOR FOR WASTE COMMINUTING DEVICE Ever J. Hammes, Racine, Wis., assignor of one-third to Quinton A. Hammes and one-third to Freda Hammes, both of Racine, Wis.

Application October 7, 1954, Serial No. 460,840 3 Claims. (Cl. 24296) The present invention relates to a rotor for waste comminuting devices commonly referred to as garbage disposal units. These devices include a receiving chamber, a cutting or shredder ring of one kind or another, and a rotor which carries the material against the shredder rings and also serves to move it down through the device to a sewer outlet.

The present invention contemplates the provision of an extremely hard cast unit made from a nickel chromium white cast iron. This material possesses an outstanding resistance to abrasion and is also extremely strong and resistant to corrosion. In addition to the specific ingredients of the material, the invention relates also to the particular construction of the rotor which creates an eflicient cutting and comminuting action.

Drawings accompany the disclosure, and the various views thereof may be briefly described as:

Figure 1, a sectional view of the rotor assembled in a waste disposal device shown partially in section.

Figure 2, a plan view of the rotor.

Figure 3, a side elevation at line 3 of Figure 1.

Figures 4 and 5, sectional views on lines 4-4 and 5---5 of Figure 2.

in the past, the rotors for waste disposal units have been made from forgings or castings which must be subsequently heat treated and machined before use. This heat treating in addition to being an expensive operation has frequently resulted in distortion of the device to make it out of round or out of shape in the direction of the axis, and it has also sometimes resulted in hair-line cracks which, if not detected, later develop into a flaw and cause breakage which might result in considerable damage to the complete machine. In fact, in some cases these cracks would develop into an open fiaw while the machines were merely stored ready for shipment.

In the present invention, the rotor is cast from the material which produces extremely accurate castings and which is so hard that it must be ground if there are any slight changes necessary in the shape after casting. No heat treating is necessary.

It is preferable that the stresses in the casting be relieved by heating to a temperature of 425 F. for a matter of three or four hours, but no high heats are required and no quenching is required. The castings come out with a Rockwell C hardness of 58 to 64 with a very dense grain structure. In some cases, the stress relieving draw operation will bring the Rockwell hardness down to about 60.

The material from which the rotor is formed preferably has the following composition in percent by weight:

Total carbon, 3.00 to 3.60 Graphitic carbon, .10 maximum Silicon, .40 to .70

Manganese, .40 to .70

Sulphur, .15

Phosphorous, .40

Nickel, 4.00 to 4.75 Chromium, 1.40 to 3.50 Remainder, cast iron Patented Apr. 29, 1958 Referring to the drawings, in Figure 1 housing units 10 and 12 of a waste disposal unit are shown confining a shredder ring 14. Within the shredder ring is a rotor 20 formed of the material above described. This rotor has a core member 24 mounted and keyed on a shaft 26 and held in position by a nut 28. In forming the rotor the center part 24 is formed of a relatively soft steel, which is a screw machine part designed to give a mechanical lock as well as a fusion bond with the hot metal that is poured on it. A low carbon machine steel is used, such as B-1 1, 12 or 13, which has been found to be more freely machinable than some other low carbon steels.

As seen in Figure 2, the metal part 24 has outer axial notches 30 and also has some annular beads 32 which create a mechanical lock between the cast part and the center. The part 24 has a bottom flange 34 which underlies a portion of the casting. After the part 24 is completed in a screw machine, it is placed in a die where the four vertical slots 30 are broached in for the radial -mechanical lock.

After the broaching operation, the center part 24 is plated with about .0002 of an inch of pure copper. This plating assists in obtaining a molecular bond between the center part and the cast material. The center part is then placed in a pattern, and sand is placed around the pattern and the center insert. The pattern is then stripped of the sand, and the insert stays: in the sand.

The above-described cast metal is then poured into the mold and hardened, after which the part is subjected to the stress relief process above described calling for a four hour soak at 400 to 425 F., the parts being then cooled down to room temperature. After this soaking operation the part becomes very strong; and as previously indicated, the Rockwell hardness is about 60 on the C scale.

The center of the soft insert is then opened to receive the shaft 26 together with a key 36. If necessary, the outer edges of the device can be ground for circularity and balance after the center hole is formed in insert 24. The rotor plate 20 is preferably formed with an annular ring of holes 40 which serve in the operation to pass fluid through the rotor. At four spaced points enlarged holes 42 are provided for the insertion of a puller tool not shown. At four points around the bottom of the rotor legs 44 are formed radially from the center of the unit outwardly to a point adjacent the annular rim.

On the top surface of the rotor raised radial ribs 50 and 52 are provided for the purpose of keeping material moving around the shredder ring. The shredder ring is designed to cut in a clockwise or counterclockwise direction and the rib or lug 52 has a raised peak projection 54 which will keep large pieces of food waste olf-center and cause the pieces to be thrown against the stationary outer ring. It is preferable that the center of the rotor be filled by a fairly large nut so that material cannot ride on the center without being subject to the comminuting action of the device. The rib 50 is shaped to taper downwardly toward the center from the outside.

In the casting operation, it is essential that the holes 40 and 42 be formed with a radius 60 at the bottom edge since otherwise the small projections in the sand which form these holes will break off. This hole enlarging from the top to the bottom seems to increase the velocity of the liquid and fluid passing through and thus aids in cleaning out the waste chamber in the housing 12 below the rotor.

It will thus be seen that there is provided by this invention an extremely hard and wear-resistant material assess u for a rotor, which material will have a long life and which will retain the cutting edges on the ribs 56 and 52 over long periods of time. There is also provided a novel construction for mounting the rotor and for moving material on the rotor in a manner to create the most efficient cutting.

What I claim is:

l. A rotor unit for a food waste comrninuting machine for carrying food waste in a rotary path to contact with a comrninuting ring, which comprises a relatively soft center insert and an outer circular cast plate mechanically and molecnlarly bonded to said insert, said plate having radial ribs on the top surface thereof extending outwardly from said insert, at least one of said ribs having an off-center upward projection above said ribs, and means for fastening said rotor for rotation which substantially fills the space between said ribs in the center of said rotor, said rotor having an annular row of holes formed in the cast plate adjacent the outer rim having an increasing diameter from top to bottom through the plate, the plurality of said holes serving to permit insertion of a puller tool.

2. A rotor unit for a food waste comminuting machine for carrying food waste in a rotary path to contact with a comminuting ring, which comprises a circular body plate having a flat top surface provided with diametrically disposed radial ribs extending upwardly from said surface from a point adjacent the center of the unit and tapered outwardly and upwardly toward the edge of the unit, the plate being relatively thick at the central portion and having a thickness approximately half that of the central portion of that at the edges and having radial ribs on its bottom surface extending from the thickened central portion substantially to the edge of the rotor unit, said plate being composed of a cast material of extreme hardis ness, and a hub centrally of said rotor being formed of a metallic material of softer consistency than the plate being provided with notched annular beads for direct engagement with the cast plate and having an axial dimension greater than the plate at the central portion thereof, said plate being provided with spaced holes adjacent the outer edge thereof between said radial ribs.

3. A rotor unit for a food waste comminuting machine which comprises a relatively soft center insert of lowcarbon steel, and an outer circular cast plate mechanically and molecularly bonded to said insert, said plate being formed of a nickel chromium white cast iron material having a Rockwell hardness on the C scale from 58 to 62, said plate having radial ribs on the top surface thereof extending outwardly from said insert, at least one of said ribs having an off-center upward projection above said ribs, and means for fastening said rotor for rota tion which substantially fills the space between said ribs in the center of said rotor, said rotor having an annular row of holes formed in the case plate adjacent the outer rim having an increasing diameter from top to bottom through the plate, the plurality of said holes serving to permit insertion of a puller tool.

References Cited in the file of this patent UNKTED STATE, FATE N13 238,176 Speers Feb. 22, 1881 293,306 Case Feb. 12, 1884 1,197,859 Rojekof Sept. 12, 1916 1,973,263 Mitchell et a1. Sept. 11, 1934 1,988,910 Merica Jan. 22, 1935 2,097,709 Walters Nov. 2, 1937 2,562,736 Powers July 31, 1951 2,616,770 .McPherson Nov. 4, 1952 2,667,308 Hammes Ian. 26, 1954 FOREIGN PATENTS 662,729 Great Britain Dec. 12, 1951 

